In order to evaluate and guide the design and promotion strategy for a product or service, many companies use market research surveys. In a market research survey, a set of questions is posed to each of a number of people, called “respondents.” Survey questions are often directed to the respondent's personal tastes, behaviors, and preferences as they relate to the product or service. The responses to a survey's questions, aggregated across its respondents, is typically used as an estimate of how a much larger population, such as the population of all possible customers for the product or service in a particular geographic region, would in the aggregate answer the survey's questions. The extent to which this estimate is accurate is sometimes referred to as the level of representativeness of the survey's responses.
Because it is generally not possible to measure the level of representativeness of a survey's responses, it is common to use the level of representativeness of identifiable attributes of a survey's respondents as a proxy for the level of representativeness of the survey's responses. As one example, for a survey that is to represent the tastes, behaviors, and preferences of the population of a particular geographic region, it would be typical to seek a number of respondents residing in each subregion of the geographic region (such as each state, ZIP code, or area code) that is proportional to the total number of people residing in the subregion. In this way, the distribution of different values of the subregion variable for the set of respondents would match the distribution of different values of the subregion variable for the population of the region.